47RE No Overdrive
Diagnosis and Fix

A 47RE that will not go into overdrive is one of the most common complaints on second-gen Rams, and it is also one of the most over-diagnosed. Half the time the fix is a switch, a cable adjustment, or a governor pressure solenoid.

The other half, the overdrive clutch is cooked. Work the list below in order and find out which half you are in before spending money.

Step 1: The O/D Off Switch and Dash Light

The overdrive switch is the button on the end of the column shift lever. Push it and the O/D OFF lamp should come on; push again and it should go out. If it stays lit, never lights, or flickers when you move the shifter, suspect the switch or the column wiring.

A switch the PCM reads as "O/D off" holds you out of 4th forever, and no parts under the truck will change that.

Step 2: Throttle Inputs and the TV Cable

The 47RE is only partly electronic. The valve body still takes a mechanical throttle signal through the throttle valve (TV) cable. A misadjusted TV cable is the classic cause of shift problems after any throttle linkage work.

• TV cable too tight: the valve body thinks you are always on the pedal. Shifts come late and firm, and 4th may not happen at cruise.
• TV cable too loose: early, soft, slipping shifts. This burns clutches.

Adjust per the service manual: throttle at idle, TV lever held forward against its stop, then release the cable lock so the self-adjuster sets it.

V10 trucks and early 12-valve Cummins use a throttle position sensor; 24-valve Cummins trucks use an accelerator pedal position sensor (APPS) on the throttle linkage bracket. Watch the reading on a scan tool while slowly opening the throttle; it should sweep smoothly with no dropouts.

Step 3: Governor Pressure Solenoid and Sensor

This is the big one. The 47RE does not have a mechanical governor on the output shaft. The PCM commands a governor pressure solenoid, and a governor pressure sensor reports what it actually built. That pressure pushes the shift valves over. Low governor pressure means late shifts, and 4th is usually the first gear to go missing.

Common codes on these trucks: P0748 (governor pressure solenoid circuit), P1756 (governor pressure not equal to target at 15-20 psi), P1757 (governor pressure above 3 psi when requested to be 0), and P1762 (governor pressure sensor offset). A sticky solenoid often throws nothing.

Governor Pressure Test

Install a 0-100 psi gauge at the governor pressure test port on the case. At a stop in drive, governor pressure should be near zero. As road speed rises, pressure should climb smoothly and steadily. Compare readings to the service manual chart for your year.

If pressure lags, stalls, or bounces, the problem is the solenoid, the sensor, a leaking filter screen or O-ring at the governor body, or the transfer plate area of the valve body. Our 47RE governor pressure solenoid is the most common fix we see for this complaint. Replace the filter screen and O-rings at the same time.

Step 4: Overdrive Solenoid and Internal Harness

The overdrive and converter clutch solenoids share one solenoid assembly mounted on the valve body, fed through the case connector and a short internal harness. A transmission relay fault (P1765) can knock out OD and lockup together. A P0753 points at the 3-4 shift solenoid circuit.

With the harness unplugged at the case, measure resistance across the OD solenoid pins and compare to the manual spec for your year. Then check each pin to case ground. Open, shorted, or a reading that moves when you wiggle the connector are all fails.

Pull the pan and inspect the internal wiring harness where it routes over the valve body. Chafed insulation causes intermittent no-OD that comes and goes with heat. A 47RE solenoid kit and a new 47RE internal wiring harness are cheap insurance on a high-mile truck.

Step 5: Transmission Temperature Input

No overdrive and no lockup for the first few miles on a cold morning is normal. On many years the temperature signal is built into the governor pressure sensor, so a bad sensor can look like a truck that thinks it is permanently cold. Compare the scan tool reading to a real reading off the pan.

Step 6: The Overdrive Unit Itself

If the switch works, the TV cable is right, governor pressure tracks road speed, and the OD solenoid clicks and measures correctly, the problem is hard parts.

There is no overdrive band. The 47RE has a kickdown band and a low-reverse band, both in the main case. Fourth gear comes from the overdrive clutch pack, applied hydraulically by the overdrive piston. In 1st through 3rd, a heavy spring holds the direct clutch on. When the OD solenoid fires, the piston applies the overdrive clutch and releases the direct clutch.

• Burned overdrive clutch: the 3-4 shift happens, then RPM flares, or it slips back to 3rd under load. Burnt fluid, friction material in the pan.
• OD piston retainer and seals: the retainer bolts to the back of the case and carries the seals that feed the piston. Cracked retainers or hardened seals leak apply pressure, and 4th either never engages or slips.
• 3-4 accumulator: usually causes a harsh or sloppy 3-4 shift rather than no shift, but a blown seal can make 4th feel like it is not holding.
• Overdrive sprag: a failed sprag usually shows up as slipping or no drive in the lower gears, not as missing 4th.

Rebuilding the overdrive unit means compressing the direct clutch spring, which is under serious load. Use the overdrive clutch spring compressor tool. Replace the 47RE sprag clutch if it shows any roller or race wear.

Symptom to Cause

Parts and Cost

• O/D switch or wiring repair: a small part and an hour or two of column work.
• TV cable adjustment: free if you do it.
• Governor pressure solenoid and sensor: parts plus a pan drop, filter, and ATF+4 refill. Usually the best value repair on this list.
• Solenoid assembly and internal harness: similar labor, done at the same pan drop.
• Valve body: if the bores are worn or the 3-4 shift valve sticks, a Sonnax-updated, dyno-tested 47RE valve body is a bolt-in under the pan. Or add a 47RE shift kit to your own.
• Overdrive unit or full rebuild: transmission out. Use a 47RE master rebuild kit for a complete job, or an overhaul kit if you are reusing frictions that measure good.

Our opinion: never authorize a rebuild on a no-overdrive 47RE until someone has put a gauge on governor pressure and a meter on the OD solenoid.

FAQ

Is it normal for a 47RE to skip overdrive when the truck is cold?

Yes, within reason. The PCM holds off the 3-4 shift and converter lockup until the fluid warms up. If it still refuses 4th fully warmed up, something is wrong.

Does a 47RE have an overdrive band?

No. The 47RE has two bands, kickdown and low-reverse, both in the main case. Fourth gear comes from the overdrive clutch pack in the overdrive unit, applied by the overdrive piston.

Can a bad governor pressure solenoid cause no overdrive?

Yes. Governor pressure is what moves the shift valves. Low pressure means late shifts or none, and 4th usually disappears first. A gauge test confirms it.

Will a valve body swap fix no overdrive?

Only if the problem is in the valve body: a stuck 3-4 shift valve, a worn bore, or a bad solenoid assembly. It will not fix a burned overdrive clutch or leaking overdrive piston.

Can I keep driving a 47RE with no overdrive?

Short trips at moderate speed, yes, if the fluid is clean and 1-2-3 feel firm. Long highway runs in 3rd with no lockup build heat fast. If the fluid smells burnt, park it.